1. Field of the Invention
The present invention relates to a reaction chamber assembly particularly suitable for thin film deposition by self-limiting deposition processes. In particular, the reaction chamber assembly provides improved gas flow dynamics and includes and input plenum disposed between precursor or reactant sources and a reaction chamber and may include an output plenum disposed between the reaction chamber and a vacuum source. Preferably, the input plenum encloses an input plenum conduit that continuously expands in volume from a first input end to a second output end that delivers precursors into the reaction chamber. Similarly, the output plenum encloses an output plenum conduit that continuously expands in volume from a first output end to a second input end that withdraws a gas outflow from the reaction chamber.
2. The Related Art
Reaction chamber assemblies for controlling Chemical Vapor Deposition (CVD),
Physical Vapor Deposition (PVD) and other thin film deposition processes are known and widely used in various industries. In particular, thin film deposition processing equipment is widely used to apply insulating, dielectric and conductive thin film layers onto various substrates and components such as semiconductor substrates, used to make semiconductor circuit devices, and onto transparent and semitransparent glasses and other substrates, used in optical and electro-optical devices. Generally a reaction chamber assembly used for thin film deposition includes a sustainably gas tight reaction chamber with the reaction chamber configured to support one or more substrates therein with selected surfaces thereof exposed for coating by thin film layers. A chamber aperture passes through a wall of the reaction chamber to provide access to the reaction chamber to install and remove the substrates. An access door associated with the chamber aperture is provided to close and gas-seal the chamber aperture during coating operations. In production environments, the loading and unloading process may be automated, e.g. by a robotic device, and in some applications the substrates may loaded and unloaded from inside a clean room to prevent the substrates from becoming contaminated.
Conventional reaction chamber assemblies include a gas cabinet for supporting a plurality of gas supply containers filled with various pressurized gas precursors, various inert gases and other precursors that may be prepared as an aerosol, or the like, from containers filled with solid or liquid precursor materials. Conventional reaction chamber assemblies may include a vacuum pump and associated vacuum lines for drawing the reaction chamber down to a vacuum pressure and or for removing outflow from the reaction chamber. Conventional vacuum lines may include a filter or trap disposed between the reaction chamber and the vacuum pump for removing selected materials from the outflow. Conventional reaction chamber assemblies may include heaters for heating substrates, reaction chamber walls, precursors, filter or traps or other components to temperatures suitable for enhancing various chemical and physical reactions as required. In addition, some CVD and PVD reaction chamber assemblies may include a plasma generator for generating a partially ionized gas used to enhance the desired chemical and physical reactions at surfaces or the substrate.
Conventional reaction chamber assemblies include an electronic controller electrically interconnected with various devices such as pressure and temperature sensors, gas flow controllers, valves, motors, fans, pumps, actuators, and the like all used to operate the reaction chamber assembly to deposit thin films in a desired manner. The electronic controller may include one or more digital data processing elements, memories, user interface devices, video display devices, network adaptors, and the like, for carrying out logical operations, logging data, storing program steps and generally operating the reaction chamber assembly to carry out coating processes according to predefined coating recipes.
Thin film deposition processes are roughly divided into two classes, namely those configured for time-limited or self-limiting reactions and those configured for non-limiting reactions. Most industrial thin film deposition chamber assemblies are configured for performing non-limiting reactions. More specifically, non-limiting processes are preformed when two precursors are introduced into the reaction chamber simultaneously. A first precursor reacts with exposed substrate surfaces and alters the chemical or physical characteristics of the exposed substrate surfaces and thereafter a second precursor reacts with the altered substrate surfaces forming a first new solid material monolayer. Thereafter, the reaction repeats with the first precursor reacting with and altering the first monolayer and the second precursor reacting with the altered first monolayer and forming a second monolayer of new solid material. The non-limiting reaction process continues to repeat uninterrupted building up the thickness of the thin film of new solid material until the precursor supply is depleted or flushed from the reaction chamber.
In non-limiting reactions, an exposure time, defined as the length of time that a substrate is exposed to a supply of both precursors, is used as a control variable to control the thickness of a thin film deposition. In practice, the exposure time is the time between the start of the non-limiting reaction and the end of the non-limiting reaction, which is generally ended deliberately by purging the reaction chamber to remove both precursors. Non-limiting reactions are generally flux and concentration dependent. In particular, the exposure time to build up a desired thickness of a film layer depends on the chemical flux and concentration of the source material making contact with the exposed substrate surfaces wherein the source material may comprise both precursors plus a carrier gas. The chemical flux at an exposed surface is defined as a rate of flow of precursor molecules per unit area per unit time (e.g. Mols/m2/sec). The chemical concentration is defined as a percentage of the total volume of source material that is precursor available to react with the exposed surfaces. Moreover, the flux and concentration may be different for each precursor.
Because non-limiting reactions are flux and concentration dependent, reaction chamber assemblies used for non-limiting reactions, such as CDV, are typically configured to direct a flow of source material to impinge upon substrate surfaces being coated in order to keep the source material flux and concentration at the coating surface maximized during the entire exposure time. Moreover, it is desirable to mix the source materials proximate to the coating surface to increase the flux and concentration of both precursors local to reaction cites. Typically, CVD systems utilize a showerhead comprising a plurality of flow nozzles uniformly disposed over the entire surface being coated to impinge the entire surface being coated with a flow of source material during the entire exposure time. Alternately, a single flow nozzle is directed at the surface being coated to impinge an area of the surface being coated source material while the substrate is moved past the nozzle during the exposure time. In both examples, gas flow proximate to the impinge point or area tends to turbulent flow, which promotes mixing of the source material. One example of a convention CVD reaction chamber assembly that utilizes a shower head positioned opposed to a substrate surface being coated is disclosed in U.S. Pat. No. 6,960,537 to Shero et al. entitled INCORPORATION OF NITROGEN INTO HIGH K DIELECTRIC FILMS. An example of a conventional CVD reaction chamber assembly that utilizes a nozzle head positioned opposed to a substrate surface being coated is disclosed in U.S. Pat. No. 5,651,827 to Aoyama et al. entitled SINGLE-WAFER HEAT TREATEMENT APPARATUS AND METHOD OF MANUFACTURING REACTOR VESSEL USED FOR SAME. 
Self-limiting thin film deposition processes are preformed by introducing a first precursor into the reaction chamber to react with and alter the chemical or physical characteristics of the surfaces being coated, then flushing the first precursor from the reaction chamber, then introducing a second precursor the reaction chamber to react with the chemically or physically altered surfaces being coated to complete the formation a first new solid material monolayer and then flushing the second precursor from the reaction chamber. Second and subsequent thin film deposition layers may be added by repeating the cycle of introducing the first precursor to react with and alter the first new solid material monolayer, flushing the first precursor and introducing the second precursor to form a second and subsequent new solid material monolayers.
Self-limiting thin film deposition processes at least include atomic layer epitaxy (ALE) and atomic layer deposition (ALD). These processes are self-limiting because only one precursor is introduced into the reaction chamber at a time. A first precursor introduced into the reaction chamber reacts with exposed substrate surfaces, which only have a limited number of bonding cites available to react with the first precursor. The reaction between the surfaces being coated and the first precursor alters a chemical or physical state to the surface but once all of the available bonding cites form a bond with a first precursor, the reaction with the first precursor stops. A second precursor introduced into the reaction chamber reacts with the altered surfaces being coated to complete the formation of a new material monolayer but once all of the available bonding cites form a bond with the second precursor, the reaction with the second precursor stops. Thus each precursor introduction completes half a monolayer in a self-limiting manner.
Several advantages are gained by using self-limiting thin film deposition processes. These include very strict control of film thickness, since the films are formed one monolayer at a time, excellent film thickness uniformity over all exposed surfaces, good film composition homogeneity, lower reaction temperatures than CVD deposition processes, reduced precursor consumption and others. These and other advantages have lead to an increasing interest in using self-limiting thin film deposition processes in various industries. In a further distinction, extending exposure time in self-limiting thin film deposition processes does not increase layer thickness. Instead, layer thickness in self-limiting thin film deposition processes is controlled by selecting the number of deposition cycles or the number of monolayers formed. In a further advantage
However, in most early transitions to convert CVD and other non-limiting thin film deposition processes and reaction chamber assemblies designs to self-limiting thin film deposition processes and reaction chamber designs more suitable for ALE, ALD and other self limiting reactions, the reaction chamber assembly designs and operating modes have not been optimized for the self-limiting processes. In particular, self-limiting reactions are not flux or concentration dependent. With only one precursor being introduced at a time and with each substrate bonding cite only being able to bond with one precursor molecule, once bonding occurs at a bonding cite, the reaction is over and there is no need to replenish the bonding cite with additional precursor molecules. Thus there is no need to direct a flow of source material to impinge upon substrate surfaces being coated since there is no need to increase flux and concentration at bonding cites and there is no need to mix source material at bonding cites since the source material only contains one precursor at a time. Instead, it is only necessary to provide sufficient precursor volume to make contact with and react with all of the surface bonding cites available on the exposed substrate surfaces. This subtle distinction has not been recognized by ALE and ALD reaction chamber assembly designers who continue to use showerheads and other devices to direct the flow of precursors onto or proximate to substrate surfaces, examples of which are disclosed in U.S. Pat. No. 6,911,092 and U.S. Pub. App. No.s 2007/026540, 2006/0137608, 2007/0051212, which all disclose showerhead devices used in a self-limiting thin film deposition reaction chamber assembly.
A disadvantage of self-limiting thin film deposition processes is that a large number of precursor cycles is required to build up appreciable film thickness since self-limiting film layer thickness is typically less than about 10 Å per monolayer. A further disadvantage of self-limiting thin film deposition processes is that the formation of each monolayer may require four gas introduction steps, e.g. an initial chamber purge, a first precursor introduction, a chamber purge and a second precursor introduction. Thus the cycle time to build up a several hundred Å layer thickness is considerably longer than comparable thickness build up cycles by non-limiting thin film deposition processes.
Thus there is a need in the art for a reaction chamber assembly optimized for self-limiting thin film deposition processes. More specifically, there is need to reduce self-limiting monolayer formation cycle times. More generally, there is a need in the art to increase the size of reaction chambers to handle larger substrates. There is a further need in the art to increase coating throughput by providing reaction chambers suited for batch coating cycles. There is a still further need in the art, to decrease scheduled or unscheduled down time of production oriented reaction chamber systems by providing a reaction chamber that can be easily and quickly decontaminated.
List of Item Reference Numbers1000Dual Chamber Gas DepositionSystem1100Vent1110Lighting Tower1120Upper Gas Deposition Chamber1130Right Side Face1135Upper Input Gas Supply1140Frame1145Upper Cross Frame Platform1150Lower Gas Deposition Chamber1155Lower Cross Frame Platform1160Lower Input Gas supply1165Electronic Controller1170Lower Load Lock Door1180Front Face1190Upper Load Lock Door1200Single User Interface2000First ALD System2010Floor Standing System Cabinet2020Cabinet Feet2030Cabinet Front Face2040Access Door2050Door Handle2060Outer Door Panel2070Inner Door Panel2080Door Cover2090Door Heater2100Insulation Layer2110Aluminum Plate2120Resistive Heating Element3000Chamber Assembly3050Removable Back panel3060Back Perimeter flange3070Outer Volume3080Movable Access Door3090Support Structure3100Door Actuators3110Heating Elements3120Thermal Insulation Layers3125Reaction Chamber3130Right Rectangular Through Aperture3140Left Rectangular Through Aperture3150Input Plenum3160Input Plenum Flange3170Top Input Plenum Wall3180Bottom Input Plenum Wall3190Input Plenum Side Wall3200Input Plenum Side Wall3210Input Plenum Chamber3220Input Plenum End Wall3230Input Port Assembly3240Gas Supply Module3250Output Plenum3260Output Plenum Flange3270Top Output Plenum Wall3280Bottom Output Plenum Wall3290Output Plenum Side Wall3300Output Plenum Chamber3310Exit Port Assembly3320Exit Port Module3330Stop Valve3340Vacuum Pressure Gauge3350Substrate Support Surface3360Back Panel Eye Bolts3370Cone-Shaped Passage3380Liner Fasteners3390Pin Actuator Assembly3400Lift Post3410Pneumatic Cylinder and Piston Assembly3420Vacuum Bellows3430Circular Through Hole3440Guide Rods3450Stiffening Ribs4000First Reaction Chamber Assembly4010Outer Wall Assembly4020Removable Liner4025Front Face4030Input Port Assembly4040Exit Port Assembly4050Top Outer Wall4060Bottom Outer Wall4070Right Side Outer Wall4080Left Side Outer Wall4090Back Outer Wall4095Front Outer Wall4100Outer Aperture4110Outer Volume4120Resistive Heating Elements4130Top Liner Wall4140Bottom Liner Wall4150Right Side Liner Wall4160Left Side Liner Wall4170Back Liner Wall4180Chamber Aperture4190Reaction Chamber4200Rectangular Flange Portion4205Rectangular Recess4210Substrate Tray4215Clearance Gap Volume4220Bottom Substrate Tray4230Tray Supports4240Trap4250Vacuum Valve4260Cone-Shaped Conduit4270Pressure Gauge4280Cylindrical Flange4290Trap Seal4300Attaching Screws43104320First O-ring Seal4330Second O-ring Seal43404350Gas Input Port4360Gas Output Port4370Exit Port Assembly4380Tray Bottom Surface4390Stop Pins4400Tray Top Surface4500Exit Port6000Removable Liner6010Liner Base Wall6020Liner Top Wall6030Chamber Aperture6040Liner Back Wall6050Right Liner Aperture6060Left Liner Aperture6070Liner Lifting Handle6080Tooling Ball6090Liner Back Aperture7000Substrate70107015Input Plenum Liner7020Top Plenum Liner Wall7030Bottom Plenum Liner Wall7040Rectangular Fluid Conduit7050Input Plenum Liner Flange7060Bottom Plenum Liner Wall Top Surface7070(not used)7080Output Plenum Liner7090Upper Volume7100Lower Volume7110Pin Hole (Through Hole)7120Lift Pin7130Movable Pin PlateDPin Height Dimension8000Outer Wall Assembly8010Outer Aperture8020Second Outer Aperture8030Right Side Wall8040Left Side Wall8050Top Wall8060Bottom Wall8100Third Reaction Chamber8110Removable Liner8120Substrate Tray8130Tray supports8140Reaction Chamber8150Overhanging (Substrate) Edge8160Input plenum8170Exit Plenum8180Outer wall assembly8190Heating element8200Electrical Connector9005Gas Fittings9010Input Port9015Outer Tube90209030Input Port Flange9040Screws90509060Precursor Tube9070Annular Flange9080Front Edge10030 10040 Triangular Input Plenum10050 Trapezoidal Exit Plenum10060 Upper Wall Portion10070 Lower Wall Portion10080 Lower Wall Portion10090 Triangular Vertical Wall10100 Trapezoidal Vertical Wall10110 Front Vertical Flow Channel10120 Back Vertical Flow Channel